Liquefying gases



May 12, 1925. 1,537,193

M. H. ROBERTS ET AL LIQUEFYING aAsns' Filed March 4, 1919 v: Q 1 O O INVENTORS BY 6/5304 C. Ja /16 R 63mg 31 M Maw 1:04 ATTORNEYS.

Patented May 12, 1925.

MONIAGUE H. ROBERTS, or

TION OF NEW YORK.

JERSEY CITY, NEW JERSEY, OF NEW YORK, N. Y., ASSIGNORS TO AIR REDUCTION AND CLAUDE c. VAN NUYS, com any, me, A com-01m- LIQUEFYING GASES.

Application filed March 4, 1M9. Serial No. 280,515.

To all VIP/t0! it may concern ile it known that Mox'moun ll. llonuirrs. a itizen of the United States, residing in .lcrscy Uitv. Hudson (minty State oi New .lcrsov. and Cannon VAN Nnrs, a citizen of the llnited States, residing in New York city New York ilounty, State of New York, have invented certain new and useful Iniprovemcnts in Liquefying Gases; and we do hereby declare the following to be a. full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the 931119.

This invention relates to the art of liquefyiug gases and has fOIll'S object the accomplishment of certain advantageous results, among which are operation at higher tein peratures liquefaction in a single chamber, delivery of the gaseous evaporation products at relatively high pressure where desirable, rejection of certa n constituents without liquefaction thereof and avoidance of dilliculty frequently encountered as a result of solidification of carbon dioxide present in the gaseous mixture treated.

These and other objects of our invention will be readily appreciated as it is better understood by reference to the following specification when read in connection with the accompanying drawing diagrammatically illustrating an apparatus adapted for use in the accomplishment of our purpose.

Our invention employs the principles of expansion of the compressed gas with externot work, to reduce the temperature hereof, and enrichment of the liquefied products by hackward return of the liquid in contact with cold compressed gas. In processes employing these principles as heretofore practised, preliminary liquefaction of the gas is accomplished in a liquefier which is separate from the rectifying column. A portion of the compressed gas passes through the liqueticr at the initial pressure and is liquefied by indirect contact with cold rectification products from the column, to which the liquid passes from the liquetier. Another portion of the cold compressed gas passes through an engine, controlled by a suitable dynamometcr, wherein the gas is expanded with external Work and without liquefaction, although materially cooled by liquefaction the expansion operation. 'lhe-cxpandcd gas is then conveyed to the column and passes upwardly therein in indirect contact with liquid products, being thereby liquefied. The liquid product is vaporized and travels upwardly in direct contact with fresh portions of liquid, becoming thus enriched in one of the constituents of the gaseous mixture while the liquid is enriched in another constituent. Both constituents eventually leave the column in a gaseous state and serve to liquefy and cool additional quantities of incoming compressed gas.

lVe have discovered that, particularly in large installations, intended to produce large volumes of a gaseous mixture of desired composition by partial separation of the constituents of another mixture of different composition certain advantageous results are accomplished through the practice of the method as hereinafter described.

For example, we find that only a partial of the gaseous mixture is necessary and that enrichment of the product in the desired constituent may be accomplished with a large saving: of power. Higher temperatures may be employed because liquetaction is carried on at substantially the initial pressure of the incoming gas and the product may be delivered when desired at relatively high pressures for direct utilization and without further compression. Difficulties experienced, through separation of solid carbon dioxide about the valves of the expansion engine, are entirely obviated, the carbon dioxide being separated before the gas is permitted to expand. These and other advantages render the method extremely economical and efiicient and therefore advantageous in smaller as well as the larger installations in which we particularly recommend it.

In accordance with our invention the compressed gas is first subjected to heat intel-change by indirect contact with cold expanded constituent gases of the gaseous mixture treated, in preliminary exchangers and are then further cooled-without reduction of pressure in a special exchanger by indirect contact: with said constituent gases coming directly from the column. The cold compressed gases are then delivered to the bottom of the column and pass upwardly discharge the products at any therein, first in indirect contact with one of said constituent gases, which have previously been permitted to expand with external work and thereby cooled, then in indirect contact with another constituent gas which has also been permitted to expand with external work and finally to indirect contact with removed by passing the liquid through a suitable screen. Carbon dioxide cannot therefore interfere with the operation by fouling the valvesof the engine and need not be removed by preliminary treatment of the incoming gas.

Referring to the drawing 4 indicates the evaporating liquefaction products of the preliminary exchanger comprising prefercolumn. A portion of the cold compressed ably two s ells 5 and (5 each enclosing two gas is liquefied during its passage through the column and is enriched in the constituent having the highest boiling point by backward return in contact with the stream of incoming compressed gas. collects in the bottom of the column an serves to maintain the supply of evaporating liquid which acts as a cooling agent in the upper zone thereof. The unliquefied constituent and the evaporation 'product of the enriched liquid are separately conveyed to the special exchanger where they giveup a portion of their cold to the incoming compressed gas. The two streams of gas are then conveyed to expansion engines and permitted to expand with external work, whereby they are materially cooled, being then delivered to separate compartments in the column where they assist in cooling the compressed gas to the liquefying temperature, after which they are discharged through the preliminary exchangers.

From the foregoing it will be observed that the pressure of the gas undergoing liquefaction in the column is substantially the initial pressure of the gas permitting the accomplishment of the desired liquefaction with the maintenance of somewhat higher temperatures than have been customarily employed. All of the liquefaction occurs in the column and only such portions of the gas are liquefied as is essential to produce a gas of the desired enrichment in one of the constituent gases. Practically the entire operation is carried out at the initial pressure of the incoming gas and the reduction of pressure in the engines may be regulated to sure, inasmuch as the engines exhaust directly to the pressures of the gases leaving the exchanger 4 Methods heretofore employed where gas is expanded prior to lique faction, require the maintenance of a pressure from four to five times greater on the exhaust side of the engine than is necessary when employing the present invention. The cooling accomplished by expansion is the same in dropping from 5 to 1 atmosphere, for example, as in dropping from 25 to 5 atmospheres. Consequently there is a marked advantage in expanding after liquefaction because the initial pressure may be reduced. -The expans'on engines are not utilized until after the gas has passed the li uefaction zone wherein all carbon dioxide will be separated as a solid which may be The liquefied gas desired presat the ends 0' nests of tubes 7 communicating respectively with the chambers 8 and '9 at the ends of the shells. The incoming compressed gas is conveyed by a pi e 10 to a valve chamber 11, thence througi a pipe 12 to the shell 5 when it circulates about the tubes 7 and is cooled by the gases passing therethroug h. From the shell 5, the compressed gas is delivered by a pipe 13 to the valve chamber 11 in which it is irected into a pipe 14 which conveys it to the shell 6. In the latter shell the compressed gas circulates about the tubes 7 and is cooled to a still lower temperature by the cold gases in the tubes and is delivered through a pipe 15 to a valve chamber 16 and escapes through an outlet pipe 17. It will be understood that the foregoing refers to a well known form of exchanger constructed and arrange so that the cold compressed gas may be alternately directed first into either of the shells 5 or 6, permitting the warm incoming gas to melt any moisture which may congeal on the colder zones of the exchanger. The gases in the tubes 7 are preferably cold products of the separation which is carried out in the column as hereinafter described. These products are delivered through pipes 18 and 19 to the chambers 8 and 9 and are delivered to a valve casing 20 throu h pipe 21 and 22 whence they are conveye to any suitable storage receptacles or exhausted to the atmosphere as may be expedient. Other forms of exchangers may be substituted, the form described being, however. one well adapted to the purpose for which it is commonly employed.

The pipe 17 conveys the cooled compressed s to a special exc anger 23 comprising a shell 24 enclosing two bundles of tubes 25 communicatin with chambers 26 and 27 the shell. about the tubes of the special exchanger 23 and being cooled by indirect contact with gases passing through the tubes 25 the com pressed gas is delivered by a pipe 28, to a chamber 29 at the bottom of a column 30 at substantially its initial pressure. i. c., the pressure at which the gas enters the system through the pipe 10.

The column is provided with three separate chambers 31, 32 and 33. through which two sets of tubes 34 and 35 extend. The tubes 34 communicate at their lower ends with the chamber 29 and at their upper ends with an intermediate chamber 36 The After circulating all lit)

tubes convey the gas from the chamber 36 to a head 37. The chambers 31 and 32 are each divided by battles 38 into a pinrality of superposed freely communioating zones through which gas cooled as hereina l'ter explained is compelled to descend from the uppermost to the lowest zone in each chamber. Thus the incoming cold coinpresscd gas is subjected in the tubes 34 to indirect contact tirst with the warmer and then with the colder gas in each of the chambers 31 and S2. The incoming compressed gas is thus further cooled to a temperature which and at the pressure employed ensures the commencement of lique faction. the liquefied product flowing backwardly in direct contact with the incoming gas and accumulating in the chamber 29. From this chamber the liquid product is witlulrawn through a. pipe 39 past a screen a l in a chamber 40' having a removable cover 4-1 and pressure reducing valve 41 and is delivered to the uppermost of a series of superposed pans 42 in the chamber 33. Preferably a bypass t? with a controlling valve 44- is arranged about the valve 41 tor the purpose of better regulation.

The liquid overflows into the lower pans 1n the chamber 33 and surrounds the tubes 3:) through which thecompressed flowing to the head 37. The liquid is evaptr rated and the gas in the tubes 35 cone spondingly cooled. The liquid duringtlie [awkward return toward the chamber 29 becomes enriched in the more readily liqueliahlc constituent of the gaseous mixturia while the gas escaping to the head 3'? is correspondingly enriched in the i881: readily liquefiable constituent.

The vaporized gas from the chamber 2.?? and the gas from the head 3T are conveyed through pipes 45 and i t to the chamber it; and ot the special exchanger :3 and a time passing through the tum and cooling the incoming con'ipresscd s, are i'lelivered through pipes 47 and it? to engines 45) and 50 connected to suitable means {not shownl whereby the gases permitted to expand in the respective engines are caused to perform external work. From the engines 49 and 5t) pipes 51 and 52 convey the gases, cooled by their expansion, to the chambers 31 and 32 ot' the column. The gases pass downwardly in the chambers under control of the bailles I18 and are conveyed from the bottoms of the chambers to the preliminary exchangers by the pipes 18 and 19.

llv-passcs 53 and 54 having valves 5'5 and so also provided, to permit the passage of the products from the column about the engines 49 and 50. This permits a closer regulation of the engines. The valves 55 and 56 act as expansion valves and the products passing therethrough are cooled by expansion.

Our invention atlords many advantages in the production of gaseous mixtures enriched in particular constituents and will be described hereinafter as specifically applied to the liquefaction and separation of air into oxygen and nitrogen, although it is to be understood that this is merely by way of illustration and that the invention is not limited in its application to any specific gaseous mixture. 1

Compressed air at a pressure of 10 atmospheres is delivered to the exchangers 4 and is cooled therein to a temperature of approximately 100 (l. and in the special exchanger 23 to approximately 150 C. The compressed cooled air is delivered at the initial pressure to the chamber 29 of the column and is subjected therein successively to indirect contact with the expanded cold gases from the engines 49 and .50 at temperatures approximating 162 C. and then to indirect contact with liquid evaporating in the chamber 33. at a temperature approximating 160 C. The air is liquefied and the liquid enriched to a composition of substantially 40% of oxygen while the gas escaping to the head 37 is substantially pure nitrogen. The vaporized enriched liquid .air. and the nitrogen escaping from the column at substantially 152" (l. cool the incoming air in the special exchanger .23 and pass to the engines It] and 5t). where they are expanded to pressures of substantially 4 atmospheres with corresponding drop in temperature to substantially 162 C. and after cooling the air in the column are delivered by the pipes 18 and 19 to the prelimina exchanger, and are finally dc lirere. .lnrough the valve chamber 20. One of the products of the operation as above described is air containing about, 40% oxy gen hut it is to be understood that the proportion of oxygen is variable and that by an additional ltatiiltflttitlll conducted in accordance "vv tl well understood principles of the Claude column substantially pure oxygen nniy he obtained.

A. wide field exists for the utilization of oxygen or air enriched in oxygen in the various arts, among which may he mentioned iron blast and similar metallurgical procill] esses, oxidation of nitrogen in the electric V with the incoming gas,

tion, evaporating the liquid be utilized for any of the purposes for which it is adapted. It is to be noted, however, that the method and apparatus disclosed are adapted to the separation of gases without reference to particular chemical nature thereof and the invention is not limited to the separation of air into its constituents.

- Various changes may be made in the method and apparatus as hereinbefore described, withoutideparting from the spirit and scope of the invention or sacrificing any of its material advantages and various gases iuay be treated to recover their constituents or mixtures enriched in selected constituents.

I claim 1. In the liquefaction of gases, the method which comprises, liquefying a portion of the incoming compressed gas, separating the liquid and withdrawing the unliquefied portion, evaporating the liquid while maintaining a substantial pressure thereon by heat interchange with the incoming gas to hquefy a portion thereof, expanding the evaporation product and causing the expanded product to cool the incoming gas before it is subjected to heat interchange with the evaporating liquid.

2. In the liquefaction of gases, the method which comprises, liquefying a portion of the incoming compressed gas, separating the liquid and withdrawing the .unliquefied portion, evaporating the liquid whilcmaintaining a substantial interchahge with the incoming gas to liquefy a portion thereof, expanding the evaporation product with external work, thereby cooling said product and subjecting the incoming gas to heat interchange with the cooled product. 7

3.' In the liquefaction of gases, the method which comprises, liquefying a portion of the incoming compressed gas, separating the l quid and Withdrawing the unl'iqucfied portion, eva crating the liquid whilemaintaining a su stantial pressure thereon, expanding the evaporation product with external work and utilizing the cold produced to llquefly further quantities of gas.

n the liquefaction of gases, the method which comprises, liquefying a portion of the incoming eompresed gas, so aratin the liquid and withdrawing the un 'quefie porwhile maintaining a substantial pressurethereon, warming the evaporation product by heat interchange expanding the evaporation product and utilizing the cold produced to li uefy further qu'antitiesof gas.

5. In theiiquefaction of gases, the method which comprises,-liquefying a portion of the incoming compressed gas, evaporating the liquid while maintaining a substantial pres-- sure thereon, by heat interchange with further portions of the incoming gas to produce more liquid, warmmgjthe evaporation -incoming compressed gas,

pressure thereon by heat the incoming compressed gas,

product by heat interchange with the in coming gas, expanding said product and utilizing the cold produced to cool and liquefy portions of the incoming gas prior to subjecting it to the cold produced by the evaporating liquid.

6. In the liquefaction of gases, the method which comprises, liquefying a portion of the incoming compressed gas, evaporating the liquid while maintaining a substantial pressure thereon, separately expanding the'evaporation product and the unliquefied portion of the gas and utilizing the cold produced to reduce further portions of the incoming gas to a liquefying temperature.

7 In the liquefaction of gases, the method which comprises, liquefying a portion of the separating the liquid and withdrawing the unliquefied portion, evaporating the liquid while maintaining a substantial pressure thereon, warming the evaporation product and the un liquefied portion of the gas by heat inter.-

change with additional portions of incoming gas, expanding the evaporation product and unliquefied portion and utilizing the cold produced thereby to liquefy the incoming gas.

8. In the liquefaction of which comprises, liquefying a portion of the incoming compressed gas, evaporating the liquid while maintaining a substantial pres sure thereon by heat interchange with the liquefying portlon, separately expanding the evaporation product and unliquefied portion of the gas and subjecting the incoming gas to heat interchange with the expanded evaporation product and unliquefied portion prior to heat interchange with the evaporating liquid.

9. In the liquefaction of gases, the method which comprises, liquefying a port1on of evaporating the liquid while maintaining a substantial pressure thereon by heat interchange with the liquefying portion, separately withdrawing and expanding the evaporation product and unliquefied portion of the gas, and ploying the cold thus producedto hquefy additional portions of the incoming gas.

10. In the liquefaction of gases, the method which comprises, liquefying a portion of the incoming compressed gas evaporating the'liquid by heat interchange with gases, the method the liquefying portion, separately withdrawing and warming of gases, the a gas, y the em- I initial pressure, separating the liquid from and withdrawing the unliquefied portion, evaporating the liquid while maintaining a substantial pressure thereon to maintain the liquet'ying temperature, expanding the evaporation product, thereby producing additional cold and cooling the incoming gas therewith.

12. In the, liquefaction of gases, the method which comprises, compressing a gas, partially liquefying it at substantially the initial pressure, separating the liquid from and withdrawing the unliquefied portion, evaporating the liquid while maintaining a substantial pressure thereon to liqucfy further portions of the incoming gas, expanding the evaporation product with external work, thereby producing additional cold and causing a heat interchange between the expanded product and the incoming gas prior to subjecting said incoming gas to heat interchange with the evaporating liquid.

3. In the liquefaction of gases the method which comprises compressing a gas, partially liquefying it as substantially its initial pres sure, separating the liquid from and withdrawing the unliquefied portion, evaporating the liquid at a substantial pressure and supplying the cold to reduce said gas to a liquefying temperature at the pressure maintained, partially by the evaporation of the liquid formed and partially by the expansion of the evaporation product.

14. In the liquefaction of gases the method which comprises compressing a gas, partially liquefying it at substantially its initial pressure, separating the liquid from and withdrawing the unliquefied portion, evaporating the liquid at a'substantial pres-- sure and supplying cold to reduce said gas to a liquefying temperature at the pressure maintained, partially by evaporation of the liquid formed and partially by the expansion of the evaporation product, the latter being caused to cool the incoming gas prior to cooling thereof by the evaporating liquid.

15. In the liquefaction of -gases the method which comprises compressing a gas, liquefying a portion thereof at substantially its initial pressure, separating the liquid from and Withdrawing the unliquetied portion, evaporating the liquid at a substantial pressure and supplying cold to reduce said gas to a liquefying temperature at the pressure maintained, partially by evaporation of the liquid formed and partially by expansion of the evaporation product and of the unliquetied portion of the gas.

16. In the liquefaction of gases the method which comprises compressing a gas, liquefying a portion thereof at substantially its initialpressure, separating the liquid from and Withdrawing the unliq uefied portion, evaporating the liquid at a substantial pressure and supplying cold to reduce said the unliqucfied portion of flie gas, and cooling the incoming gas prior to liquefaction thereof by heat-interchange with said evaporation product and unliquelicd portion of the gas' prior to expansion thereof.

17. In the liquefaction of gases the method which comprises compressing a gas, liquefying a portion thereof at substantially its initial pressure, separating the liquid from and withdrawing the unliquefied portion, evaporating the liquid at a substantial pressure and supplying cold to reduce said gas to a liqueiying temperature at the pressure maintained, partially by evaporating the liquid formed and partially by expansion of the evaporation product, and cooling the incoming gas prior to liquc faction thereof by heat interchange with the evaporation product prior to expansion thereof.

18. In an apparatus for the liquefaction of gases, the combination of a column having separate compartments, means travels ing the compartments for conveying the gas through said compartments in succession, an expansion engine for receiving the evaporation product from the uppermost compartinent and means for conveying the expanded evaporation productto a lower compartment.

19. In an apparatus for the liquefaction of gases, the combination of a colmun having separate compartments, means for conveying the gas through said compartments in succession, expansion engines for receiving the unliqueiied portion'of the gas and the evaporation product of the liquid from the uppermost compartment and means for conveying the expanded gas and evaporation product to lower compartments.

20 In an apparatus for the liquefaction of gases, the combination of a column having separate compartments, a plurality of tubes for conveying the gas through said compartments in succession, means for delivering the liquid formed in said tubes to the upper compartment, an engine to receive the'evaporation product from the upper compartment and means for conveying the expanded evaporation product to a lower compartment.

21. In an apparatus of the character described, the combination of a column having separate compartments, a plurality of tubes for conveying the gas throughsaid compartments in succession, means for delivering the liquid formed in said tubes to the upper compartment, an exchanger whereby the evaporation product from said upper compartment is allowed to cool the incoming gas, an engine to receive said evapollll ration roduet from said exchanger and means or ponveying the expalnded eve ration product from said engine to a, ower compartment.

22. In the liquefaction of gases, method whiohcomprises liquefymg e portion of the ineoming compressed gas, vaporizin the liquid to liquefy further portions of t e gas,

another portion of the product without external work.

drawing and ex an the P expanding a portion of the 10 product with external work and expanding 23. In the liquefaction of gases, the method which comprises liquefying a portion of the incomin compressed gas, withing the unliquefied portion, the expansion being uocomplished part-ielly with and partially without external work.

In testimony whereof we affix our signatnres.

MONTAGUE H. ROBERTS. CLAUDE o. VAN NUYS.

rationroduct from said exchanger and means or conveying the expalnded evaporation product from said engine to a. ower compartment.

22. In the liquefaction of gases, the

method which comprises liquefying a portion of the incoming compressed gas, vaporizing the liquid to liquefy further portions of the gas, expanding a portion of the product with external work and expanding another portion of the product without external work.

23. In the liquefaction of gases, the method which comprises liquefying a portion of the incomin compressed gas, withdrawing and expan ing the unliquefied por- MONTAGUE H. ROBERTS. CLAUDE C. VAN NUYS.

Certificate of Correction.

n is hereby certified that in Letters Patent No. 1,537,193,

tague H. Roberts, '01? Jersey or'k, N. Y., for an improvement in Liquefying lication of Mon an Nuys, of New upon the a Claude C.

Gases, errors appear in the printed specification requiring Page 3, line 79, for 100 0. read -100 0.; line 80, for 150 C. an

lty, New ersey, and

correction as follows: read 160 0.,

ines 86, 95, and 100, for 162 C. read -162 0., and line 89, for 160 C. read ,160 0.; and that the said Letters Patent should be read with these cor-. rections therein that the same .may conform to the record of the case in the Patent [slam] Signed and sealed this-16th day of June, A. 1925.

, KARL FENNING,

Acting C'onmiesimwr of Patenta.

anted Ma 12, 1925,

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,537,193, anted Ma 12, 1925, upon the a plication of Monte ue H. Roberts, of Jersey Cit New ersey, and Claude 0. E an Nuys, of New ork, N. Y., for an improvement in Liquefying Gases, errors appear in the printed specification requiring correction as follows: Pa 3, line 79, for 100 C. read 100 0.; line 80, for 150 C. read 1I50 0., en ines 86, 95, and 100, for 16 C. read --16'2 0., and line 89, for 160 C.

read ,-160 0.; and that'the said Letters Patent should be read with these cor-.

rections therein that the same may conform to the record of the case in the Patent Signed and sealed this16th day of June, A. D. 1925.

[am] r KARL FENNING,

Acting Gomnz'ssioner of Patente. 

